Therma-Stor Products Group XT150H - Manual (Page 6)

3.4C Ducting for Fresh Air
Fresh air can be brought into the structure by connecting an
insulated duct from outside to the 6" Ultra-Aire XT150H inlet and
by turning on the fan switch or activating the humidity control (on
units with the humidity control panel). Activate the ventilation timer
on units with the ventilating and humidity control panel to bring in
fresh air. Refer to Section 4.5 for programming instructions for the
ventilation timer. Advantages of this form of ventilation include:
1. Outside air is filtered before entering the building.
2. Outside air will be dehumidified before entering if the Ultra-
Aire XT150H is running in dehumidification mode.
3. Drawing air from outside and blowing inside aids in slightly
pressurizing the structure. This helps prevent dirty and humid
air from entering elsewhere. It also reduces the potential for
carcinogenic radon gas to enter and provides make-up air for
open combustion and exhaust devices like the clothes drier,
fireplace, and water heater.
4. Adequate exhaust fans are recommended in the bath rooms
and kitchen.
In cold climates or areas where the outdoor dew point is low
at times, ventilation can be used to dehumidify the structure.
This is accomplished by bringing the dry, low dew point air into
the structure during these times. This approach is often more
economical than running the dehumidifier to remove excess
moisture from the structure. In cold climates, it is critical to
adequately ventilate to reduce the inside moisture content to
avoid moisture accumulating in the wall cavities. For example; in a
house that experiences condensation on the interior surface of the
windows during the winter, increasing the amount of ventilation will
often cure the problem.
An insulated 6" diameter duct is generally sufficient to provide up
to 125 CFM of outside air. Large quantities of outside air will either
positively or negatively impact the performance of the Ultra-Aire
XT150H, depending upon inside and outside air conditions. Consult
the factory by calling 1-800-533-7533 for recommendations
regarding the use of higher flows with your specific application.
The outside air duct should be connected to the 6" round collar
on the filter enclosure of the unit. The 6" round collar includes a
manual damper. Adjust the manual damper to provide the desired
amount of fresh air for ventilation. The amount of fresh air should
be based on the size and occupancy of the residence. If you are
unsure of your ventilation air requirements, consult the factory by
calling 1-800-533-7533 for assistance.
3.4D Installation in a Basement or Crawlspace
with an Existing Forced Air HVAC System
It is recommended that a new, separate return duct be installed for
the Ultra-Aire XT150H from a central area of the house. If this is not
possible, and if the existing system has multiple returns, select one
to disconnect from the existing forced air system and use it for the
dedicated Ultra-Aire XT150H return. Always select a return from a
central location in the structure in an area that is always open to
the rest of the structure. Do not use a return from a room that may
have its door closed much of the time.
If the structure in which the Ultra-Aire XT150H is to be installed has
an existing forced air HVAC system, utilize the HVAC system to make
the Ultra-Aire XT150H installation easier.
Basement Installation: Install a separate 10" return for the Ultra-
Aire XT150H in a central area of the structure. Duct the supply of the
Ultra-Aire XT150H to an optional 10" x 10" x 10" tee/damper that
is 20% open to the basement. This allows the ability to discharge a
variable amount of dehumidified air into a basement that may not
be well served by the existing duct system. Duct the other side of
the tee to the air supply of the existing HVAC system. A backdraft
damper is required in the duct between the 10" tee and the central
supply duct to prevent air from being discharged into the basement
during central fan operation. Connect a duct from outside to the
6" collar of the Ultra-Aire XT150H if you wish to provide fresh air
ventilation.
Crawl Space Installation: Install a separate return for the Ultra-
Aire XT150H in a central area of the structure. Duct the supply of
the Ultra-Aire XT150H to a 10" x 10" x 10" tee/damper that is 20%
open to the crawl space if desired. Duct the other side of the tee
to the air supply of the existing HVAC system ventilation. Connect
an insulated duct from outside to the 6" collar of the Ultra-Aire
XT150H if you wish to provide optional fresh air.
FOR HVAC INSTALLER ONLY
6 Ultra-Aire XT150H Installer’s & Owner’s Manual